Hellcat wrote: Savez wrote: Maryland was not in rebellion. There was only threat of rebellion. Maryland had not seceded.
I don't think Maryland could have joined the Confederacy. I believe the state was under martial law during the war. Lee had hoped to get Maryland Confederate sympathizers to join his army during the Maryland campaign, but the state itself didn't really have a chance due to DC. There was no way Lincoln was going to let the capital be surrounded by Confederate territory and thus cut off from the rest of the nation.

some fine studies show that Maryland, though a slave state, had been losing slaves and slaveholders for years.

The sharpsburg campaign was into exactly the wrong part of the state to entice southern sympathizers...